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Systematic reviews as a ‘lens of evidence’: Determinants of benefits and harms of breast cancer screening
Author(s) -
Mandrik Olena,
Zielonke Nadine,
Meheus Filip,
Severens J.L. Hans,
Guha Neela,
Herrero Acosta Rolando,
Murillo Raul
Publication year - 2019
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.32211
Subject(s) - overdiagnosis , medicine , mammography , systematic review , breast cancer , observational study , breast cancer screening , gynecology , medline , family medicine , cancer , political science , law
This systematic review, stimulated by inconsistency in secondary evidence, reports the benefits and harms of breast cancer (BC) screening and their determinants according to systematic reviews. A systematic search, which identified 9,976 abstracts, led to the inclusion of 58 reviews. BC mortality reduction with screening mammography was 15–25% in trials and 28–56% in observational studies in all age groups, and the risk of stage III+ cancers was reduced for women older than 49 years. Overdiagnosis due to mammography was 1–60% in trials and 1–12% in studies with a low risk of bias, and cumulative false‐positive rates were lower with biennial than annual screening (3–17% vs 0.01–41%). There is no consistency in the reviews’ conclusions about the magnitude of BC mortality reduction among women younger than 50 years or older than 69 years, or determinants of benefits and harms of mammography, including the type of mammography (digital vs screen‐film), the number of views and the screening interval. Similarly, there was no solid evidence on determinants of benefits and harms or BC mortality reduction with screening by ultrasonography or clinical breast examination (sensitivity ranges, 54–84% and 47–69%, respectively), and strong evidence of unfavourable benefit‐to‐harm ratio with breast self‐examination. The reviews’ conclusions were not dependent on the quality of the reviews or publication date. Systematic reviews on mammography screening, mainly from high‐income countries, systematically disagree on the interpretation of the benefit‐to‐harm ratio. Future reviews are unlikely to clarify the discrepancies unless new original studies are published.